Outgassing Rates and Compositions of the Released Gases from Optical Fiber Panel and Photocathode Glass Used for Low-light-level Image Intensifiers

Abstract

To analyze the vacuum failure mechanism of low-light-level image intensifiers in depth, the outgassing rates and compositions of the released gases from optical fiber panel and photocathode glass used for the image intensifiers were investigated by static pressure-rising method and residual gas analysis. The investigation results show that the outgassing rate of the optical fiber panel at a baking temperature of 150°C is only about one order of magnitude higher than that at 23°C, while the outgassing rate of the photocathode glass at 150°C is about two orders of magnitude higher than that at 23°C. As the static accumulation time of gas releasing extends, the outgassing rate of the optical fiber panel linearly increases at 23°C, and it remains basically unchanged at 150°C, while for the photocathode glass, its outgassing rate increases rapidly firstly and then tends to be stable gradually both at 23°C and 150°C. The gas compositions released from the optical fiber panel and photocathode glass at 23°C mainly include H2O, H2, N2/CO and CO2. After experiencing the vacuum baking at 150°C, the releasing ratio of H2O gas from the optical fiber panel decreased just slightly, which indicates that the vacuum baking degassing for the photocathode glass is relatively difficult; by contrast, the releasing ratio of H2O gas from the photocathode glass significantly decreased, and that of H2 gas obviously increased. These results can provide experimental bases for further optimizing the component materials and fabrication process of low-light-level image intensifiers.